Muscle relaxers, or muscle relaxants, are medications used to treat muscle spasms or muscle spasticity.
Muscle spasms or cramps are sudden, involuntary contractions of a muscle or group of muscles. They can be caused by too much muscle strain and lead to pain. They’re associated with conditions such as lower back pain, neck pain, and fibromyalgia.
Muscle spasticity, on the other hand, is a continuous muscle spasm that causes stiffness, rigidity, or tightness that can interfere with normal walking, talking, or movement. Muscle spasticity is caused by injury to parts of the brain or spinal cord involved with movement. Conditions that can cause muscle spasticity include multiple sclerosis (MS), cerebral palsy, and amyotrophic lateral sclerosis (ALS).
Prescription drugs can help relieve the pain and discomfort from muscle spasms or spasticity. In addition, certain over-the-counter medications may be used to treat aches and pains associated with muscle spasms.
Prescription medications are divided into two groups: antispasmodics and antispastics. Antispasmodics are used to treat muscle spasms, and antispastics are used to treat muscle spasticity. Some antispasmodics, such as tizanidine, can be used to treat muscle spasticity. However, antispastics should not be used to treat muscle spasms.
Antispasmodics: Centrally acting skeletal muscle relaxants (SMRs)
Centrally acting SMRs are used in addition to rest and physical therapy to help relieve muscle spasms. They’re thought to work by causing a sedative effect or by preventing your nerves from sending pain signals to your brain.
You should only use these muscle relaxants for up to 2 or 3 weeks. The safety of longer-term use is not yet known.
While antispasmodics can be used to treat muscle spasms, they have not been shown to work better than nonsteroidal anti-inflammatory drugs (NSAIDs) or acetaminophen. In addition, they have more side effects than NSAIDs or acetaminophen.
The more common side effects of centrally acting SMRs include:
- reddish-purple or orange urine
- lowered blood pressure upon standing
You should talk to your doctor about the benefits and risks of these medications for the treatment of your muscle spasms.
List of centrally acting SMRs
|Generic name||Brand name||Form||Generic available|
|chlorzoxazone||Parafon Forte, Lorzone||tablet||yes|
|cyclobenzaprine||Fexmid, Flexeril, Amrix||tablet, extended-release capsule||tablet only|
Antispastics are used to treat muscle spasticity. They should not be used to treat muscle spasms. These drugs include:
Baclofen: Baclofen (Lioresal) is used to relieve spasticity caused by MS. It’s not fully understood how it works, but it seems to block nerve signals from the spinal cord that cause muscles to spasm. Side effects can include drowsiness, dizziness, weakness, and fatigue.
Dantrolene: Dantrolene (Dantrium) is used to treat muscle spasms caused by spinal cord injury, stroke, cerebral palsy, or MS. It works by acting directly on the skeletal muscle to relax the muscle spasm. Side effects can include drowsiness, dizziness, lightheadedness, and fatigue.
Diazepam: Diazepam (Valium) is used to relieve muscle spasms caused by inflammation, trauma, or muscle spasticity. It works by increasing the activity of a certain neurotransmitter to decrease the occurrence of muscle spasms. Diazepam is a sedative. Side effects can include drowsiness, fatigue, and muscle weakness.
List of antispastics
|Generic name||Brand name||Form||Generic available|
|baclofen||Lioresal, Gablofen, Lioresal||tablet, injection||yes|
|diazepam||Valium||oral suspension, tablet, injection||yes|
Muscle relaxants such as carisoprodol and diazepam can be habit forming. Be sure to take your medication exactly as prescribed by your doctor.
Muscle relaxants can also cause withdrawal symptoms, such as seizures or hallucinations (sensing things that aren’t real). Do not suddenly stop taking your medication, especially if you’ve been taking it for a long time.
Also, muscle relaxants depress your central nervous system (CNS), making it hard to pay attention or stay awake. While taking a muscle relaxant, avoid activities that require mental alertness or coordination, such as driving or using heavy machinery.
You should not take muscle relaxants with:
- CNS depressant drugs, such as opioids or psychotropics
- sleeping medications
- herbal supplements such as St. John’s wort
Talk to your doctor about how you can safely use muscle relaxants if you:
- are older than 65 years
- have a mental health problem or brain disorder
- have liver problems
Muscle Relaxer Abuse
Muscle relaxers have a potential for abuse and addiction. Prolonged use can lead to increased tolerance and physical dependence, especially with Soma.3 For this reason, muscle relaxers are intended as a short-term treatment not to be prescribed for more than 2-3 weeks.
Unfortunately, many individuals take muscle relaxers alone or in combination with other illicit drugs for nonmedical reasons, such as to produce or enhance feelings of euphoria and dissociation. According to the Drug Enforcement Administration, Soma is one of the most commonly diverted drugs in the United States.2 Evidence also indicates prevalent misuse of Flexeril. In 2010 there were over 12,000 emergency room visits associated with Flexeril, and in 2016 over 10,000 calls to the Poison Control Centers had involved Flexeril.1
Muscle relaxer abuse can lead to serious dangers such as an increased risk of overdose, which can result in:
- respiratory depression
- cardiac arrest
Alcohol and Muscle Relaxers
Like muscle relaxers, alcohol also depresses the central nervous system. When alcohol is consumed with muscle relaxers the side effects are exacerbated. This can be very dangerous, leading to symptoms like:
- Blurred vision
- Urine retention
- Extreme dizziness
- Extreme drowsiness
- Low blood pressure
- Memory problems
- Liver damage
- Increased risk of overdose
It is recommended to not drive or operate heavy machinery when under the influence of muscle relaxers. It is especially important to avoid drinking, as combining muscle relaxers with alcohol greatly increases your risk of an accident.
Withdrawal and Treatment
Regular use of muscle relaxers causes the brain to become used to its effects. If you attempt to suddenly stop using muscle relaxers you may experience withdrawal symptoms. Depending on the specific drug and how long you have been using it, there are various treatment options available to help you overcome your addiction.
For many people, Flexeril withdrawal causes mild symptoms such as nausea, headache, drowsiness, malaise, and discomfort. Symptoms tend to peak about 2-4 days after you last took the Flexeril, although in some people withdrawal symptoms may last for up to 1-2 weeks. For many people Flexeril detox can be done at home. However, if Flexeril addiction is accompanied by alcohol or opioid abuse the withdrawal symptoms from these other substances can be severe. In these situations, it may be best to undergo professional medical detox.
Soma withdrawal is usually more severe and can include symptoms like hallucinations and seizures. For your safety and comfort, it is often best to find an inpatient treatment program that includes a detox program to manage withdrawal symptoms. After detox patients can transition into the actual treatment phase of the program. Some people may not require a supervised detox program and will be able to undergo treatment on an outpatient basis.
Off-label medications for spasticity
Doctors can use certain medications to treat spasticity even when the drugs are not approved for that purpose by the U.S. Food and Drug Association (FDA). This is called off-label drug use. The following drugs are not actually muscle relaxants, but they can still help relieve symptoms of spasticity.
Benzodiazepines are sedatives that can help relax muscles. They work by increasing the effects of certain neurotransmitters, which are chemicals that relay messages between your brain cells.
Examples of benzodiazepines include:
- clonazepam (Klonopin)
- lorazepam (Ativan)
- alprazolam (Xanax)
Side effects of benzodiazepines can include drowsiness and problems with balance and memory. These drugs can also be habit forming.
Clonidine (Kapvay) is thought to work by preventing your nerves from sending pain signals to your brain or by causing a sedative effect.
Clonidine should not be used with other muscle relaxants. Taking it with similar drugs increases your risk of side effects. For instance, taking clonidine with tizanidine can cause very low blood pressure.
Clonidine is available in brand-name and generic versions.
Gabapentin (Neurontin) is an anticonvulsant drug typically used to relieve seizures. It’s not fully known how gabapentin works to relieve muscle spasticity. Gabapentin is available in brand-name and generic versions.
OTC treatment is recommended as first-line therapy for muscle spasms caused by conditions such as acute lower back pain or tension headache. This means you should try OTC treatments before prescription medications.
OTC treatment options include nonsteroidal anti-inflammatory drugs (NSAIDs), acetaminophen, or a combination of both. Your doctor or pharmacist can help you choose an OTC treatment.
Nonsteroidal anti-inflammatory drugs (NSAIDs)
NSAIDs work by blocking your body from making certain substances that cause inflammation and pain. NSAIDs are available in generic and brand-name versions. They’re typically sold over the counter. Stronger versions are available by prescription.
NSAIDs come as oral tablets, capsules, or suspensions. They also come as chewable tablets for children. Side effects of these drugs can include upset stomach and dizziness.
Examples of NSAIDs include:
- ibuprofen (Advil, Motrin)
- naproxen (Aleve)
Acetaminophen (Tylenol) is thought to work by blocking your body from making certain substances that cause pain. Acetaminophen is available in generic and brand-name versions. It comes as immediate-release and extended release oral tablets and capsules, orally disintegrating tablets, chewable tablets, and oral solutions.
The more common side effects of acetaminophen can include nausea and upset stomach.
You can often manage your muscle spasm or spasticity symptoms on your own, but in some cases, you may need medical advice or care. Be sure to call your doctor if you:
- have spasticity for the first time and don’t know the cause
- notice the spasticity is getting more severe, happening more often, or making tasks difficult
- have severe and frequent muscle spasms
- notice deformity of the parts of your body affected by muscle spasms
- have side effects from your muscle relaxant
- have a “frozen joint” due to contracture that decreases your range of motion or causes pressure sores
- have increasing discomfort or pain
It’s important to treat both spasticity and muscle spasms. Severe, long-term spasticity can lead to muscle contracture, which can decrease your range of motion or leave the affected joints permanently bent. And muscle spasms can not only be uncomfortable, they can also be a sign of an underlying medical problem.
Your muscle spasms or spasticity are likely treatable with rest, physical therapy, medications, or all of the above. Work with your doctor to put together a care plan that can ease your pain and get you moving comfortably again.
Types of Skeletal Muscle Relaxants
Skeletal muscle relaxants, also called muscle relaxers, may be divided into two classes: antispasmodics and antispastics. Antispasmodics are agents that specifically treat muscle spasms. Muscle spasm occurs as a result of injury to muscles, tendons, or ligaments and is often synonymous with low back sprain or strain. Antispastics (sometimes referred to as spasmolytics) are agents that specifically treat muscle spasticity. Muscle spasticity is a condition in which the patient experiences continuous muscle spasms as a result of spinal motor neuron overactivity. This overexcitation manifests as clonus; stiffness; rigidity and tightness; and difficulty with walking, movement, and, occasionally, talking. A systematic review of studies on leg spasticity epidemiology reported a prevalence of 28% to 38% in stroke patients, 41% to 66% in multiple sclerosis patients, and 13% in patients with traumatic brain injury.
According to the American College of Physicians (ACP), first-line therapy for acute low back pain (pain lasting <4 wk) consists of nonpharmacologic measures such as stretching, heat, and physical therapy. Antispasmodics, antispastics, and NSAIDs are all considered second-line therapy. Patient characteristics will influence the drug choice. Unlike NSAIDs, however, skeletal muscle relaxants do not have any disease-modifying properties for low back pain and provide only symptomatic improvement. Chronic use of these medications is not recommended because little to no data exist on their safety and efficacy with long-term use. The ACP does not recommend skeletal muscle relaxants in patients with chronic low back pain (pain lasting >12 wk) because of a lack of efficacy and safety data.
The Geriatric Lexi-Drugs database recommends the avoidance of muscle relaxants other than diazepam and tizanidine in patients older than age 65 years because efficacy and safety have not been established in geriatric patients.9 However, all muscle relaxants, including tizanidine and diazepam, are on the Beers Criteria list.3
Potential for Harm in Geriatric Patients
Because antispastics and antispasmodics work within the central nervous system, their side effects can pose a unique risk for geriatric patients. Compared with the average adult, geriatric patients are at increased risk for falls because of unsteady gait, loss of coordination or muscle strength, and other age-related declines in mobility and cognition. Common side effects of antispastic and antispasmodic medications include dizziness, drowsiness, and hypotension; therefore, a geriatric patient’s risk for falls and fractures can increase when skeletal muscle relaxants are used. One study showed that geriatric patients who took muscle relaxants were 2.25 times more likely to visit the emergency department for a fall or fracture and 1.56 times more likely to be hospitalized for a fall or fracture than patients who did not take these medications. Another study found that skeletal muscle relaxant users older than age 65 years were 1.32 times more likely to have an injury than patients who did not use skeletal muscle relaxants. More specifically, patients who took carisoprodol, cyclobenzaprine, and methocarbamol, respectively, were 1.73 times, 1.22 times, and 1.42 times more likely to have experienced injury compared with patients without a history of skeletal muscle relaxant use.
Muscle relaxants for pain management in rheumatoid arthritis
This summary of a Cochrane review presents what we know from research about the effect of muscle relaxants on pain in patients with rheumatoid arthritis.
The review shows that in people with rheumatoid arthritis:
‐ Muscle relaxants may not improve pain when taken as a single dose or for up to a two week period
‐ We are uncertain whether muscle relaxants affect functional status because of the very low quality of the evidence
‐ No trials were found that evaluated whether muscle relaxants affect quality of life
‐ No trials were found that evaluated whether antidepressants affect sleep
‐ We are uncertain whether muscle relaxants affect mood because of the very low quality of the evidence
We also do not have precise information about side effects and complications. This is particularly true for rare but serious side effects. Possible side effects may include feeling tired or nauseous, headaches, blurred vision, a dry mouth, sexual dysfunction, or becoming dizzy or constipated. Rare complications may include increased suicidal thinking, liver inflammation, or a reduced white cell count.
What is rheumatoid arthritis and what are muscle relaxants?
When you have rheumatoid arthritis your immune system, which normally fights infection, attacks the lining of your joints. This makes your joints swollen, stiff, and painful. The small joints of your hands and feet are usually affected first. There is no cure for rheumatoid arthritis at present, so the treatments aim to relieve pain and stiffness and improve your ability to move.
Muscle relaxants can be used to treat anxiety and promote sleep, and some people believe they may also reduce pain by acting on the nerves that cause pain, but this remains controversial. Muscle relaxants include drugs that reduce muscle spasm (for example benzodiazepines such as diazepam (Valium), Xanax, Ativan and non‐benzodiazepines such as Skelaxin, Muscol) and drugs that prevent increased muscle tone (baclofen and dantrolene).
Best estimates of what happens to people with rheumatoid arthritis who take muscle relaxants:
Pain at 24 hours:
‐ Non‐significant result.
Pain at 1 to 2 weeks:
‐ Non‐significant result.
Withdrawal due to adverse events, after 2 weeks:
‐ Non‐significant result.
Total adverse events:
‐ 49 more people out of 100 experienced an adverse event, after 1 to 2 weeks, when they took a muscle relaxant (absolute difference 49%),
‐ 52 out of 100 people who took a muscle relaxant suffered an adverse event,
‐ 3 out of 100 people who took a placebo suffered an adverse event.
Central nervous system (CNS) adverse events:
‐ 33 more people out of 100 experienced a CNS adverse event, after 1 to 2 weeks, when they took a muscle relaxant (absolute difference 33%),
‐ 39 out of 100 people who took a muscle relaxant suffered a CNS adverse event,
‐ 6 out of 100 people who took a placebo relaxant suffered a CNS adverse event.
This record should be cited as:
This is a Cochrane review abstract and plain language summary, prepared and maintained by The Cochrane Collaboration, currently published in the Cochrane Database of Systematic Reviews [Issue and date] © [year] The Cochrane Collaboration. Published by John Wiley and Sons, Ltd.. The full text of the review is available in The Cochrane Library (ISSN 1464‐780X).